Abstract
The number of chromosomes was determined in mitosis, the course of meiosis was analysed and the degree of pollen viability determined in plants with intermediate enzymatic phenotypes between Aconitum napellus and A. variegatum. One allotriploid plant was found with 2n=24 and a group of plants with 2n=32 showing disturbances in mitosis and meiosis. In mitosis somatic reduction and polysomaty were observed and in meiosis monads, diads, triads and polyads were present. These plants are considered as introgressive hybrids arising owing to a small scale gene flow from A. variegatum to A. napellus.